Soil Triangle Calculator

Check soil texture from sand, silt, and clay values. Review normalized fractions, class results, charts, and exportable summaries for field reporting.

Calculator Form

Plotly Graph

Example Data Table

Sample Sand (%) Silt (%) Clay (%) Class Use Case
EX-01 82 10 8 Loamy Sand Drainage layer
EX-02 40 40 20 Loam General fill review
EX-03 25 35 40 Clay Settlement concern
EX-04 55 25 20 Sandy Clay Loam Compaction check

About This Soil Triangle Calculator

This soil triangle calculator helps construction teams interpret soil texture quickly. It uses sand, silt, and clay percentages to place a sample inside a texture triangle. That result supports better decisions during earthwork, compaction planning, drainage review, and material selection.

Why soil texture matters

Texture influences bearing behavior, permeability, workability, and moisture response. Sandy soils drain faster and compact differently. Silty soils can lose strength when wet. Clay-rich soils may shrink, swell, and retain water for longer periods. A clear soil texture class improves field communication and reduces reporting delays.

What this calculator does

The tool accepts two or three particle fractions. When one fraction is missing, it computes the remainder from the 100 percent total. It can also normalize values when laboratory data totals slightly above or below 100 because of rounding. That saves time during fast design checks and site reporting.

Useful outputs for construction work

Besides the soil class, the page returns dominant fraction, fines content, coarse to fine ratio, texture index, and ternary coordinates. Optional moisture content, liquid limit, and plastic limit fields extend the review. This is useful when teams compare field classification with consistency behavior and constructability observations.

Reporting and visualization benefits

The graph plots the sample on a ternary chart. That visual check helps confirm whether the sample trends toward sand, silt, or clay. Export buttons create a CSV summary and a PDF-ready report view. These outputs support internal records, consultant coordination, and quality documentation.

Best practice note

Use laboratory-tested percentages whenever possible. Field estimates are helpful for screening, but final design should rely on verified gradation and index properties. This calculator is best used as a practical interpretation tool for construction planning, soil discussions, and quick documentation.

Formula Used

1. Total fraction: Total = Sand + Silt + Clay

2. Missing fraction: Missing value = 100 − other two fractions

3. Normalized fraction: Adjusted value = (Component / Total) × 100

4. Fines content: Fines = Silt + Clay

5. Coarse/Fine ratio: Ratio = Sand / (Silt + Clay)

6. Plasticity index: PI = Liquid Limit − Plastic Limit

7. Ternary coordinates: X = Silt + Clay/2, Y = Clay × 0.8660254038

The soil class is assigned from the normalized percentages using common USDA-style texture boundaries. This gives a reliable soil-texture label for many construction review tasks.

How to Use This Calculator

  1. Enter sample details, if available.
  2. Input sand, silt, and clay percentages.
  3. You may leave one fraction blank.
  4. Choose whether normalization should be applied.
  5. Optionally enter moisture and Atterberg limit data.
  6. Select the preferred decimal precision.
  7. Press the calculate button.
  8. Review the result above the form.
  9. Check the graph and summary indicators.
  10. Download CSV or PDF for reporting.

FAQs

1. What does the soil triangle show?

It shows how sand, silt, and clay combine to define a soil texture class. The class helps estimate drainage, workability, and general construction behavior.

2. Can I leave one fraction blank?

Yes. If two valid fractions are entered, the calculator computes the third fraction so the total becomes 100 percent.

3. Why use normalization?

Normalization adjusts values when lab percentages do not total exactly 100 because of rounding or minor reporting differences. It preserves the relative proportions.

4. Is this suitable for field screening?

Yes. It is useful for quick field interpretation and early planning. Final engineering decisions should still use verified laboratory results and project specifications.

5. What is fines content?

Fines content is the sum of silt and clay. It helps indicate how much of the sample may affect moisture sensitivity and reduced drainage.

6. Why include liquid and plastic limits?

These values provide a simple consistency check. They help compare soil texture with plasticity behavior during handling, compaction, and moisture changes.

7. Does the graph support reporting?

Yes. The ternary plot gives a quick visual reference for presentations, site records, and consultant discussions about soil classification trends.

8. Can I export the results?

Yes. The page includes CSV and PDF export options, making it easier to share calculation summaries with project teams.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.